1. Field of the Invention
The present invention relates to a conductive sheet and a capacitive touch panel, for example suitable for use in a projected capacitive touch panel.
2. Description of the Related Art
Touch panels have attracted much attention in recent years. For example, some touch panels, which use ITO (indium tin oxide) as an electrode material to make an electrode matrix less visible, have been disclosed (see, Japanese Laid-Open Patent Publication Nos. 2010-086684 and 05-224818, etc.)
Though the touch panel has currently been used mainly in small devices such as PDAs (personal digital assistants) and mobile phones, it is expected to be used in large devices such as personal computer displays.
The conventional electrode is composed of the ITO (indium tin oxide) and therefore has a high resistance of about several hundred ohm/sq. Thus, when the conventional touch panel is used in the large device in the above future trend, the large-sized touch panel has a low current transfer rate between the electrodes, and thereby exhibits a low response speed (taking a long time to detect the position touched with a finger tip).
A large number of lattices made of thin wires of a metal (thin metal wires) may be arranged to form an electrode with a lowered surface resistance. Touch panels using the electrode of the thin metal wires are known from International Publication No. WO 97/018508, Japanese Laid-Open Patent Publication No. 2003-099185, U.S. Pat. No. 5,113,041, International Publication No. WO 95/027334, U.S. Patent Application Publication No. 2004/0239650, U.S. Pat. No. 7,202,859, International Publication No. WO 2010/013679, etc.
Conductive sheets according to International Publication No. WO 97/018508, Japanese Laid-Open Patent Publication No. 2003-099185, U.S. Pat. No. 5,113,041 (FIG. 1a), and International Publication No. WO 95/027334 each have a first conductive pattern formed by arranging a large number of the thin metal wires in the vertical direction, a second conductive pattern formed by arranging a large number of the thin metal wires in the horizontal direction, and an insulating layer disposed between the first and second conductive patterns.
Conductive sheets according to U.S. Patent Application Publication No. 2004/0239650 and U.S. Pat. No. 7,202,859 each have a first conductive pattern formed by arranging the thin metal wires each having a plurality of S-shaped portions in the vertical direction and a second conductive pattern formed by arranging the thin metal wires each having a plurality of S-shaped portions in the horizontal direction.
A touch switch according to International Publication No. WO 2010/013679 has a substrate, a plurality of first electrodes arranged at regular intervals on one surface of the substrate, and a plurality of second electrodes arranged at regular intervals on the other surface of the substrate, and the first and second electrodes are arranged into a lattice pattern. The touch switch is attached to the front of a display device.
In addition, in International Publication No. WO 2010/013679, the first electrode shown in FIG. 7 has a plurality of sensing sections each containing a combination of a plurality of small lattices. The sensing sections are connected via two connection paths of conductive wires in a connection part.
However, in the above examples, when one thin metal wire is broken, an address associated with the broken wire cannot be recognized disadvantageously. In the touch switch of International Publication No. WO 2010/013679, the sensing sections of the first electrode are connected only via two connection paths. Therefore, it is highly probable that both the two connection paths are broken to completely disconnect the sensing sections.